Balloon for medical tube and medical tube equipped with the same

ABSTRACT

A cylindrical balloon for medical tubes, which is susceptible to bending operations, comprises a low stretchable section formed, by a partial cross-linking treatment, on the balloon along the circumferential direction thereof. A medical tube equipped with a balloon comprises a shaft tube for being inserted into a living body, a cylindrical balloon liquid-tightly connected to the shaft tube at the periphery on the tip thereof, a first lumen which is formed within the shaft tube and which communicates with the interior of the balloon, and at least one second lumen which is formed within the shaft tube and which is opened at the tip of the shaft tube; or comprises a shaft tube which is inserted into a living body, a cylindrical balloon, one end of which is liquid-tightly connected to the shaft tube at the tip thereof, a long tool for medical treatments or for diagnoses, whose tip portion is liquid-tightly connected to the other end of the balloon directly or indirectly, and a lumen which is formed within the shaft tube and communicates with the interior of the balloon so that a liquid can pass through the balloon and which accommodates the long tool for medical treatments or for diagnoses, wherein the cylindrical balloon is the same as that defined above.

BACKGROUND OF THE INVENTION

[0001] (A) Field of the Invention

[0002] The present invention relates to a balloon for medical tubes anda medical tube equipped with such a balloon. More specifically, thepresent invention pertains to a balloon for medical tubes, which hasvariable bendability, which can impart, to a medical tube to be insertedinto a living body for examinations and/or treatments, adirection-selecting function (the ability to select the course ordirection of the tip of the medical tube) due to the variable orarbitrary bendability of the balloon or can impart, to the medical tube,a function of separating tissues by the variable bending motions of theballoon, while making the most use of the difference in the partialstretchability of the balloon induced when a pressurized fluid isinjected therein, as well as a medical tube equipped with such aballoon.

[0003] (b) Description of the Prior Art

[0004] Operations performed in the past requiring severe operativeinvasion has gradually been superseded by the operative techniques withless operative invasion. For instance, there have spectacularly beenspread widely therapeutic methods with minimum invasion therapy (MIT),mainly based on techniques which make use of catheters and endoscopes,such as PTCA, PTA and stent techniques, atelectomy, embolization andoperations performed under an endoscope.

[0005] In particular, in the field of the catheter techniques, therehave been developed a variety of balloon-catheters in order to, forinstance, supply a medical fluid or an infusion solution to a specificsite in a body cavity such as a blood vessel, a digestive tract, auterine tube or a ureter, or to expand a site with a stenosis by theexpansive force of a balloon.

[0006] However, a higher operative technique will require thedevelopment of a catheter whose tip portion has an ability to select itscourse of advancement by the bending of the same. In respect of thebending mechanism of the tip of a catheter, various structures have beenproposed, but they are all complicated and the diameter of the catheterswould inevitably be increased.

[0007] In addition, a catheter has conventionally been used only for thebody cavities, except for a part of operations performed underendoscopes. However, there has been desired for the development of acatheter technique which is not limited only to the transluminalapproach techniques which make use of biological tracts and/or cavitiessuch as blood vessels, as the area of catheter application is widelyexpanded.

[0008] A cavity should be formed within a variety of tissues by a lessfrictional means to treat a target site by letting a catheter arrive ata desired site from the exterior of a biological tract or cavity, unlikethe technique which makes use of the biological tract or cavity. To thisend, tissues should often be separated over a wide area. After thecatheter arrives at the desired portion, various tools may be adapted tocarry out diagnosis and/or treatments through the use of the multiplelumens of the catheter.

[0009] As a method for separating tissues, the tip of a catheter maycontinuously be deformed and moved after the catheter arrives at thedesired site on the tissue to be separated. Various structures have beenproposed, as the bending mechanisms of the tip of the catheter, but allof them are very complicated and the diameter of the catheters wouldinevitably be increased. Moreover, there has not yet been developed anymultifunctional catheter designed from the viewpoint of thenon-transluminal approach to the tissue separation from the outside ofthe biological tract or cavity.

SUMMARY OF THE INVENTION

[0010] The present invention has been developed to solve the foregoingvarious problems associated with the conventional techniques andaccordingly, an object of the present invention is to provide a balloonfor medical tubes, which has variable bendability, which can impart adirection-selecting function due to the variable bendability of theballoon to a medical tube inserted into a living body for examinationsand/or treatments, while making the most use of the difference inpartial stretchability of the balloon induced when a pressurized fluidis injected therein, which has a simple structure and whose diameter cansubstantially be reduced, as well as a medical tube equipped with such aballoon.

[0011] Another object of the present invention is to provide a medicaltubular structure equipped with a balloon designed from the viewpoint ofthe non-transluminal approach to the tissue separation from the outsideof the biological tract or cavity, which thus has a function forseparating biological tissues by the variable ability of the balloon toundergo bending motions, which has a simple structure and whose diametercan be reduced.

[0012] The inventors of this invention have conducted various studies toachieve the aforementioned objects and have found that variable bendingability can be imparted to a balloon and a direction-selecting functioncan thus be imparted thereto. In other words, a low stretchable sectionis partially formed on a cylindrical balloon along its circumferentialdirection by a cross-linking treatment to thus ensure a partialdifference in the stretchability of the balloon. Accordingly, theballoon can expand to a large extent on the side of the high stretchablesection, while the balloon on the side of the low stretchable sectioncan expand to a lesser extent, when a pressurized fluid is injectedtherein. Thus, the balloon undergoes bending towards the side of the lowstretchable section and the degree of the bending can be controlled byappropriately adjusting the pressure of the pressurized fluid.Accordingly, the inventors have completed an aspect of the presentinvention on the basis of the foregoing findings.

[0013] Alternatively, the inventors have also found the following. Acylindrical balloon is partially subjected to a cross-linking treatmentto thus form at least two low stretchable sections over less than a halfof the circumferential region on the cylindrical balloon, whichpartially extends in the axial direction of the balloon, these sectionshaving low stretchability are arranged in such a manner that thepositions thereof are deviated from one another in the axial directionof the balloon, preferably these sections substantially do not overlapwith each other in the axial direction of the balloon, and they arearranged in the opposite circumferential directions of the balloon.Thus, the balloon can expand to a large extent on the side of the highstretchable section, while the balloon on the side of the lowstretchable section can expand to a lesser extent, when a pressurizedfluid is injected therein. Accordingly, the balloon undergoes bending inan S-shaped form, towards the side of the low stretchable section andthe degree of the bending can be controlled by appropriately adjustingthe pressure of the pressurized fluid. Accordingly, an ability ofvariable bending motions can be imparted to the balloon by applying apulsative pressure of a pressurized fluid to the balloon and atissue-separating function can thus be imparted thereto. Accordingly,the inventors have likewise completed another aspect of the presentinvention.

[0014] According to an aspect of the present invention, there isprovided a cylindrical balloon for medical tubes, which has an abilityto bend and which comprises a section having low stretchability (lowstretchable section) partially formed, by a cross-linking treatment, onthe balloon along the circumferential direction thereof.

[0015] In the balloon for medical tubes according to preferredembodiment of the present invention, the low stretchable section whichis formed by a partial cross-linking treatment extends, over less than ahalf of the circumferential region on the cylindrical balloon, along theaxial direction thereof; or a first low stretchable section which isformed by a partial cross-linking treatment partially extends, over lessthan a half of the circumferential region on the cylindrical balloon,along the axial direction thereof, while a second low stretchablesection which is formed by a partial cross-linking treatment partiallyextends, over less than a half of the circumferential region on thecylindrical balloon, along the axial direction thereof, and the firstand second low stretchable sections are circumferentially arranged inopposite directions of the balloon and are also arranged in such amanner that the positions thereof are deviated from one another in theaxial direction of the balloon. However, the arrangement of these lowstretchable sections is not limited to the foregoing embodiments orpatterns. For instance, the sections may helically extend in the axialdirection of the balloon or extend at an angle with respect to the axialdirection of the balloon, or further at least three such sections may bearranged alternately and oppositely along the circumferential directionof the balloon.

[0016] According to another aspect of the present invention, there isalso provided a medical tube equipped with a balloon, which comprises:

[0017] a shaft tube for being inserted into a living body;

[0018] a cylindrical balloon liquid-tightly connected to the shaft tubeat the periphery of the tip thereof;

[0019] a first lumen which is provided within the shaft tube andcommunicates with the interior of the balloon; and

[0020] at least one second lumen which is formed within the shaft tubeand is opened at the tip thereof;

[0021] wherein the cylindrical balloon comprises a low stretchablesection which is partially formed on the circumferential region on theballoon by a cross-linking treatment.

[0022] In this respect, the foregoing cylindrical balloon used comprisesa first low stretchable section, which is formed by a partialcross-linking treatment and which partially extends, over less than ahalf of the circumferential region on the balloon, along the axialdirection thereof; and a second low stretchable section, which is formedby a partial cross-linking treatment and which partially extends, overless than a half of the circumferential region on the cylindricalballoon, along the axial direction of the balloon; the first and secondsections being circumferentially arranged in opposite directions of theballoon and arranged in such a manner that the positions thereof aredeviated from one another (or they are not in line with each other) inthe axial direction of the balloon. The use of the cylindrical ballooncan ensure the achievement of a sufficient tissue-separating functiondue to the variable bending motions of the balloon.

[0023] According to a further aspect of the present invention, there-isalso provided a medical tube equipped with a balloon, which comprises:

[0024] a shaft tube for being inserted into a living body;

[0025] a cylindrical balloon, one end of which is liquid-tightlyconnected to the shaft tube at the tip thereof;

[0026] a long tool for medical treatments or for diagnoses, whose tipportion is liquid-tightly connected to the other end of the balloondirectly or indirectly; and

[0027] a first lumen which is formed within the shaft tube andcommunicates with the interior of the balloon so that a liquid can passthrough the balloon and which accommodates the long tool for medicaltreatments or for diagnoses; or a medical tube equipped with a balloon,which comprises:

[0028] a shaft tube for being inserted into a living body;

[0029] a cylindrical balloon, one end of which is liquid-tightlyconnected to the shaft tube at the tip thereof;

[0030] a long tool for medical treatments or for diagnoses, whose tipportion is liquid-tightly connected to the other end of the balloondirectly or indirectly;

[0031] a first lumen which is formed within the shaft tube andcommunicates with the interior of the balloon so that a liquid can passthrough the balloon and which accommodates the long tool for medicaltreatments or for diagnoses; and

[0032] at least one second lumen which is formed within the shaft tubeand is opened at the periphery of the tip thereof; wherein thecylindrical balloon comprises an area having low extensibility which ispartially formed on the peripheral portion of the balloon by across-linking treatment.

BRIEF DESCRIPTION OF THE DRAWINGS

[0033]FIG. 1 is a perspective diagram showing an embodiment of theballoon for medical tubes according to the present invention;

[0034]FIG. 2 is a cross sectional view taken along the line II-II inFIG. 1;

[0035]FIG. 3 is a perspective diagram showing another embodiment of theballoon for medical tubes according to the present invention;

[0036]FIG. 4 is a cross sectional view showing a part of a firstembodiment of the medical tube equipped with a balloon according to thepresent invention;

[0037]FIG. 5 is a cross sectional view taken along the line V-V in FIG.4;

[0038]FIG. 6 is a cross sectional view showing another example of thefirst embodiment of the medical tube equipped with a balloon accordingto the present invention;

[0039]FIG. 7 is a cross sectional view showing a part of a secondembodiment of the medical tube equipped with a balloon according to thepresent invention;

[0040]FIG. 8 is a cross sectional view showing a part of a thirdembodiment of the medical tube equipped with a balloon according to thepresent invention;

[0041]FIG. 9 is a cross sectional view showing another example of thethird embodiment of the medical tube equipped with a balloon accordingto the present invention;

[0042]FIG. 10 is a cross sectional view showing the balloon, in its bentstate, of the medical tube equipped with a balloon shown in FIG. 7; and

[0043]FIG. 11 is a cross sectional view showing the balloon, in itsS-shaped bent state, of the medical tube equipped with a balloon shownin FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0044] In the present invention, examples of materials from which theballoon is formed include various kinds of polymer materials, forinstance, various kinds of polyolefins such as polyethylenes such as lowdensity polyethylene, linear low density polyethylene, medium densitypolyethylene and high density polyethylene; polypropylene andethylene-propylene copolymer; modified polyolefins such as modifiedpolyethylene and modified polypropylene; ethylene-vinyl acetatecopolymer (EVA); ethylene-ethyl acrylate copolymer; soft polyvinylchloride; silicone (for instance, siloxane) copolymers; fluorineplastics such as polytetrafluoroethylene; various kinds of dienepolymers; various kinds of elastomers such as polyamide elastomers andolefinic elastomer; and other various polymeric materials such asnatural rubber, polyurethane, silicone, polyisoprene and polyamide.Among these materials, preferably used herein are natural rubber,polyethylene, modified polyethylene, soft polyvinyl chloride andsilicone, since they have high flexibility and can easily becross-linked, with polyethylene and modified polyethylene being morepreferred and low density polyethylene being particularly preferred.

[0045] In the present invention, these materials may be used alone, butthey may also be used in the form of polymer alloys obtained by blendingwith, as minor components, other resin materials in an amount which doesnot interfere with the cross-linking of the materials and the extensionof the resulting balloon or obtained by copolymerization with such otherresin materials. In this respect, the term “polymer alloys” herein usedrefers to the concept which embraces polymer blends, graft copolymers,block copolymers and random copolymers.

[0046] Moreover, materials from which the balloon is formed may likewiseinclude those which can be cross-linked, by nature, when it isirradiated with γ-rays or electron rays and the like or combinations ofmaterials which are hardly cross-linked by nature, with a variety ofcross-linking agents. In addition, it is also possible to use a materialcapable of being easily cross-linked by nature to which a cross-linkingagent is additionally added.

[0047] In respect of the balloon according to the present invention, alow stretchable section can easily be formed on only a part of theballoon along the circumferential direction thereof by cross-linking theballoon in such a manner that the former has an extent of cross-linking(degree of cross-linking) different from that of the remaining sectionof the balloon along the circumferential direction thereof, whereby onecan secure a sufficient difference between the percentages of elongationof the low and high stretchable sections. Accordingly, the balloon canbe bent to a considerable extent by incorporating such a balloon into amedical tube and then injecting a fluid into the balloon. In the balloonof the present invention, the low stretchable section distributed alongthe circumferential direction of the balloon can be formed without usinga material different from that used for forming the remaining section ofthe balloon. In other words, the whole of the balloon may be formed froma single material and then only a part of the balloon in thecircumferential direction thereof is cross-linked. This may eliminateany problem which possibly arises when the balloon is formed from twodifferent materials, for instance, any separation and break of these twomaterials at the boundary therebetween and accordingly, highly safeballoons can stably be produced.

[0048] The cross-linking treatment used in the present invention may,for instance, be the radiation cross-linking method wherein materialssuch as polyethylene and soft polyvinyl chloride which are susceptibleto cross-linking by nature are irradiated with, for instance,high-energy radiations such as electron rays and γ-rays (in particularcases, they also include, for instance, X-rays, β-rays, heavy chargedparticle beams and neutron beams) and ultraviolet light rays;cross-linking treatments wherein a variety of cross-linking agents areincorporated into polymeric materials and then irradiated with, forinstance, high-energy radiations such as electron rays and γ-rays (inparticular cases, they also include, for instance, X-rays, β-rays, heavycharged particle beams and neutron beams) and ultraviolet light rays; orcross-linking treatments in which polymeric materials are cross-linkedby the application of heat.

[0049] The cross-linking agents usable herein may be selected from awide variety of conventionally known ones which can preferably becombined with plastic materials used. In addition, the cross-linkingagents may properly be selected depending on the cross-linking meansselected such as cross-linking by irradiation with electron rays, γ-raysand ultraviolet rays and cross-linking by heating. Specific examples ofcross-linking agents include organic peroxides such as2,4-dichlorobenzoyl peroxide, benzoyl peroxide,1,1-di-(t-butylperoxy)-3,3,5-trimethyl cyclohexane,n-butyl-4,4′-di-(t-butylperoxy)valerate, α,α′-bis(t-butylperoxydiisopropyl) benzene, 2,5-dimethyl-2,5-di-(t-butylperoxy)hexyne-3,di-t-butyl peroxide, 2,5-dimethyl-2,5-di-(t-butylperoxy)hexane,t-butylperoxy cumene and dicumyl peroxide; sulfur atom-containingcompounds such as sulfur, sulfur chloride and dithiol; cross-linkingagents which can generate radicals through, for instance, thermaldecomposition, redox decomposition and ionique decomposition and whereinthe resulting radicals pick up hydrogen atoms to thus form crosslinks,such as aminoazobenzene, quinone and polynitrobenzene; or various kindsof acrylates, methacrylates or triesters such as β-acryloyloxyethylhydrogen succinate, lauryl acrylate, ethylene glycol dimethacrylate,diethylene glycol dimethacrylate, triethylene glycol dimethacrylate,polyethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate,1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate,polypropylene glycol diacrylate, 2,2-bis[4-(acryloxy.diethoxy)phenyl]propane, 2-hydroxy-1-acryloxy-3-methacryloxy propane,trimethylolpropane trimethacrylate, trimethylolpropane triacrylate,tetramethylolmethane triacrylate, tetramethylolmethane tetraacrylate,ditrimethylolpropane tetraacrylate, di(meth)acrylate, trimethacrylateand tetra(meth) acrylate.

[0050] When using such a cross-linking agent, a balloon which comprisessections, distributed along the circumferential direction thereof,having a content of a cross-linking agent higher than that in theremaining sections is formed by, for instance, extrusion molding or blowmolding using a combination of a cross-linking agent-containing resinand a resin free of any cross-linking agent, or a combination of a resinhaving a relatively high content of a cross-linking agent and a resinhaving a relatively low content thereof and then the balloon isirradiated with the foregoing electron rays or ultraviolet rays or heatis applied thereto to thus induce a difference in physical propertiesbetween the sections formed from the foregoing two kinds of resins. Inthis case, the dose of, for instance, ultraviolet rays for irradiationor the quantity of heat to be applied to the balloon may be uniform overthe whole balloon in the circumferential direction or may be selectedsuch that the section having a higher content of the cross-linking agentis irradiated or heated to a higher extent as compared with theremaining sections. In case where the cross-linking agent is onlypartially added to the balloon along its circumferential direction, onlythe corresponding sections may be irradiated with radiant rays or heatedto form crosslinks or control the physical properties of the sections.

[0051] In case where a cross-linking agent is incorporated into astarting resin, the resin containing the cross-linking agent may bedifferent from that free of any cross-linking agent (or that containingit in a small amount), but these resins are preferably identical orsimilar to one another (same polymer group, for instance, polyamide andpolyamide elastomer, and as other combination, PET and polyesterelastomer). In addition, these resins are preferably compatible with oneanother and, in this sense, combinations of the same kind of polymermaterials are preferably used in the present invention.

[0052] Among the foregoing cross-linking treatments, the simplest is toform crosslinks by the radiation cross-linking. This method permits theprecise control of the positions and shapes of the low stretchablesection formed on the balloon by the use of an appropriate mask (or abarrier material) in a uniform radiation field and thus the lowstretchable section can be formed in various embodiments such as anembodiment in which the section extends along the axial direction, anembodiment in which a first low stretchable section and a second lowstretchable section are present on the opposite sides along thecircumferential direction of a cylindrical balloon and they are not inline with each other in the axial direction of the balloon, anembodiment wherein the section helically extends along the axialdirection of the balloon, an embodiment wherein the section obliquelyextends with respect to the axial direction of the balloon or a patternwherein at least three sections are alternately arranged along thecircumferential direction of the balloon.

[0053] The balloon for medical tubes and the medical tube equipped withsuch a balloon according to the present invention will be described inmore detail below, with reference to the embodiments as shown in theattached figures.

[0054]FIG. 1 is a perspective diagram showing the balloon for medicaltubes according to a first embodiment of the present invention and FIG.2 is a cross sectional view taken along the line II-II in FIG. 1. Aswill be seen from FIGS. 1 and 2, the balloon for medical tubes accordingto the first embodiment of the present invention comprises a relativelylow stretchable section 1 which is formed by a selective cross-linkingtreatment and a relatively high stretchable section 2 and the relativelylow stretchable section 1 extends, over less than a half of thecircumferential region on the cylindrical balloon, along the axialdirection of the balloon, respectively.

[0055]FIG. 3 is a perspective diagram showing the balloon for medicaltubes according to another embodiment of the present invention, theballoon as shown in this figure comprises first and second relativelylow stretchable sections 1A and 1B which are formed by a selectivecross-linking treatment and a relatively high stretchable section 2, thefirst low stretchable section 1A partially extends over less than ahalf, for instance, about half of the circumferential region on thecylindrical balloon, along the axial direction of the balloon, while thesecond low stretchable section 1B partially extends over less than ahalf, for instance, about half of the circumferential region on thecylindrical balloon, along the axial direction of the balloon, thesections 1A and 1B are present on the opposite sides of the balloonrespectively and they are deviated from one another in the axialdirection of the balloon, preferably they substantially do not overlapwith each other in the axial direction of the balloon.

[0056] In the foregoing low stretchable sections 1, 1A, 1B, thestretchability may continuously or stepwise be changed betweenneighboring sections distributed along the circumferential direction ofthe balloon and the rate of the low stretchable section 1, 1A, 1B withrespect to the whole circumferential area of the balloon is preferablynot more than 30% and more preferably not more than 10%. In addition,the low stretchable section 1, 1A, 1B may extend over only a part of thelength on the balloon in the axial direction or may continuously orintermittently extend over the entire length thereof, depending on thedesired degree of bending and the curved shape of the balloon observedwhen using a medical tube equipped with such a balloon.

[0057] A cylindrical balloon including two low stretchable sections isshown in FIG. 3, but a cylindrical balloon comprising at least threesuch low stretchable sections may likewise be used in the presentinvention. For instance, when the balloon comprises three such sections,the first low stretchable section extends over a part of thecircumferential direction of the balloon and over about ⅓ time thelength of the balloon in the axial direction, the second low stretchablesection extends over a part of the circumferential direction of theballoon and over about ⅓ time the length of the balloon in the axialdirection and the third low stretchable section extends over a part ofthe circumferential direction of the balloon and over about ⅓ time thelength of the balloon in the axial direction. In this case, the threelow stretchable sections may be arranged as follows: the first andsecond sections are present on the opposite sides of the balloon in thecircumferential direction, while the first and third sections arepresent on the same side of the balloon in the circumferentialdirection, and these three sections are distributed on the side of theballoon in such a manner that they are not in line with each other inthe axial direction of the balloon.

[0058] The difference in stretchability can be imparted to the balloonby appropriately changing mechanical properties such as the rate ofdrawing, elasticity modulus, rigidity and hardness of the materialconstituting the balloon, or physical properties such as the thicknessof the balloon to thus establish a difference in each value betweensections on the balloon, but the cross-linking treatment is the simplestmethod for establishing such a difference and the position and the shapeof the low stretchable section 1, 1A, 1B formed on the balloon canprecisely be controlled. Therefore, the balloon of the present inventionis limited to a cylindrical balloon for medical tubes, which is equippedwith low stretchable sections formed by a cross-linking method.

[0059] The cross-linking treatment used in the invention willhereinafter be explained in more detail while taking, as an example, thecase where a balloon having a partial difference in the stretchabilityis formed by selectively establishing a difference in the stretchabilityby the electron radiation cross-linking. For instance, a balloon isformed using a low density polyethylene and the stretchability thereofis changed by changing the dose of electron rays, i.e., the degree ofcross-linking along the circumferential direction. Preferably, the highstretchable section 2 formed on the balloon is irradiated with electronrays at a dose ranging from 5 to 35 Mrad, while the low stretchablesection 1, 1A, 1B is irradiated with electron rays at a dose of 3 to 10Mrad higher than that used for the irradiation of the high stretchablesection. More preferably, the high stretchable section 2 is irradiatedwith electron rays at a dose ranging from 20 to 25 Mrad, while thelatter is irradiated with electron rays at a dose of 3 to 5 Mrad higherthan that used for the irradiation of the former.

[0060]FIG. 4 is a cross sectional view showing a part of a firstembodiment of the medical tube equipped with a balloon according to thepresent invention and FIG. 5 is a cross sectional view taken along theline V-V in FIG. 4. As will be seen from FIGS. 4 and 5, the medical tubeaccording to the first embodiment of the present invention comprises ashaft tube 3 for being inserted into a living body and a cylindricalballoon 4 which is liquid-tightly connected to the shaft tube 3 at theperiphery of the tip thereof. Furthermore, a first lumen 5 is providedwithin the shaft tube 3 and communicates with the interior of theballoon 4 and at least one second lumen 6 is provided within the shafttube 3 and is opened at the tip of the tube. In this embodiment of thepresent invention, the cylindrical balloon 4 has a particular shape andspecific properties as has been described above in connection with FIGS.1 and 2 or FIG. 3.

[0061] The foregoing shaft tube 3 is constituted by, for instance, apolymeric material having a certain degree of flexibility, such aspolyethylene, polyethylene terephthalate, soft polyvinyl chloride,polypropylene, polyurethane, polyamide, polyimide,polytetrafluoroethylene, silicone rubber or ethylene-vinyl acetatecopolymer.

[0062] Moreover, the outer surface of the shaft tube 3 and the balloon 4may be coated with a low-frictional material such as a hydrophilicpolymer (e.g., maleic anhydride copolymer) or a fluorine-containingresin (e.g., polytetrafluoroethylene) in order to reduce the frictionbetween the tube and the balloon and a body cavity encountered when themedical tube is inserted into the body cavity.

[0063] In the medical tube according to the first embodiment of thepresent invention, a tubular reinforcing material is preferably embeddedin the shaft tube 3 in the proximity of the periphery thereof over apart or the whole length of the tube 3 so as to surround each lumen 5,6. Examples of the reinforcing material include those produced frommetallic materials such as stainless steel and superelastic alloys;those produced from resin materials such as polyamide, polyethylene,polypropylene, polyester, polyimide and ABS resins; and thoseconstituted by filament-like bodies of, for instance, carbon fibers,with braided bodies obtained by crossing such filament-like bodies eachother in the form of a braid being particularly preferred. Theincorporation of such a reinforcing material permits an increase in thetorsional rigidity of the shaft tube 3 and this in turn ensures theeffective transfer, to the tip of the shaft tube, of the rotatory powergenerated when the tube is rotated at the base end thereof, i.e., theimprovement of the torque-transfer characteristics of the tube.Moreover, the use of such a reinforcing material also inhibits andobstruction or stenosis of the lumen 5, 6 even when the shaft tube 3 isbent, in particular, at a sharp angle.

[0064] In addition, the X-ray radiogpaque property is preferablyimparted to the shaft tube 3 so that the position of the shaft tube 3can be confirmed by the radioscopy, when it is inserted into a livingbody. Examples of the method for imparting the susceptibility to theX-ray radiography include those comprising the step of incorporating,into the material for the shaft tube 3, a radiopaque substance such asbarium sulfate, bismuth oxide or tungsten and those comprising the stepof embedding a marker comprising such a radiopaque substance in apredetermined position on the tube 3 or adhering such a marker to thesurface thereof.

[0065] In the medical tube according to the first embodiment of thepresent invention, a pressure can be applied to the first lumen 5 whichcommunicates with the interior of the balloon by connecting it to apressing fluid source through a fluid pressure controller; by connectingit to a pressing fluid source through a fluid pressure controllercapable of applying a pulsatile pressure; or by applying a pulsatilepressure to the balloon using a pulsating pump for generating pulsatilepressure. The pressing fluid may be a gas or a liquid. The fluidpressure controller can adjust the pressure, to be applied to theballoon, to the range of preferably from 0 to 15 atm and the pulsefrequency of the pressure when it is applied to the balloon in a seriesof pulses ranges from 1 to 20 Hz and the minimum and maximum levels ofthe pulsatile pressure applied to the balloon are 0 atm and 1˜5 atm,respectively. The angle of bending or that of S-shaped bending variesarbitrarily or in any series of pulses in response to the appliedpressure or the pressure variation and the balloon is in general bent atan angle ranging from 0 to 90 deg. Furthermore, the application of apulse-like pressure gives rise to, for instance, S-shaped bendingmotions. It is preferred that the balloon does not undergo any S-shapedbending form when the minimum pulse-like pressure is applied, but it isbent in an S-shaped form when the maximum pulse-like pressure isapplied. The pulse frequency of the pressure applied to the balloonvaries depending on the energy required for the separation of biologicaltissues, but preferably it in general falls within the range of from 1to 20 Hz. The fluid pressure controller may be adjusted manually orelectrically.

[0066] As has been discussed above, the medical tube of the presentinvention comprises the relatively low stretchable section and therelatively high stretchable section and accordingly, if a fluid pressureis applied to the balloon, the balloon undergoes bending towards theside of the relatively low stretchable section and the shaft tube isalso bent in response thereto. In other words, the extent of the bendingcan continuously be changed in proportion to the applied fluid pressure.The shape of the bent balloon is changed depending on the shape andarrangement, on the balloon, of the relatively low stretchablesection(s). Therefore, the balloon permits appropriate selection ofbranchings of the biological tubular cavities and the medical tube canbe forced even in tissues other than the biological tubular cavitieswhile appropriately selecting the course of progress. In addition, thedirection of the opening at the tip of the shaft tube can also bechanged continuously by bending the shaft tube and accordingly, the siteto be examined or treated can precisely be specified.

[0067] In the medical tube according to the first embodiment of thepresent invention, at least one second lumen 6 which is opened at thetip of the shaft tube may serve as a channel through which a guide wire,tools for medical treatments or diagnoses, or the like can be inserted.Examples of such tools for medical treatments or diagnoses areendoscopes, forceps, a variety of treatment tools, brushes for cytologicexamination, needles, probes (for use in, for instance, lithocenosis,laser ray-irradiation and abrasion) emitting or generatinghigh-frequency waves, ultrasonics and hydraulic impulse waves;, and avariety of sensors and leading wires therefor.

[0068] Moreover, the medical tube of the present invention permits theinjection of a fluid into biological tissues or tubular organs or thesuction of a fluid, through the space formed between the tools formedical treatments or diagnoses and the wall of the lumen, or throughanother second lumen 6. More specifically, the medical tube is insertedinto a living body to thus administer, for instance, a medical fluidinto indwelling biological tissues and tubular organs, or the tube isused as a flush channel for injecting a transparent liquid (such asphysiological saline and a glucose injection) used for forcing out abody fluid such as the blood or the bile which obstruct the view whenobserving biological tissues or tubular organs with an endoscope.

[0069] The medical tube shown in FIGS. 4 and 5 comprises a single secondlumen 6, but the medical tube according to the present invention may beequipped with two or more second lumens 6 as shown in FIG. 6 dependingon the applications thereof. Such a shaft tube provided with multiplelumens and the method for producing the same are known from the priorart.

[0070]FIG. 7 is a cross sectional view showing a part of the medicaltube according to a second embodiment of the present invention. Themedical tube according to a second embodiment of the present inventioncomprises a shaft tube 3 which is inserted into a living body; acylindrical balloon 4 liquid-tightly connected to the shaft tube 3 atthe one end thereof; and a long tool 7 for medical treatments ordiagnoses whose tip portion is directly or indirectly connected to theother end of the cylindrical balloon in a liquid-tight manner. A firstlumen 5 which is provided within the shaft tube 3 and communicates withthe interior of the balloon to thus allow the passage of a fluidtherethrough and the long tool 7 for medical treatments or diagnoses areaccommodated in the first lumen 5. In this embodiment of the presentinvention, the cylindrical balloon 4 has a particular shape and specificproperties as has been described above in connection with FIGS. 1 and 2or FIG. 3.

[0071] Examples of such tools 7 for medical treatments or diagnoses areendoscopes, forceps, a variety of treatment tools, brushes for cytologicexamination, probes (for use in, for instance, lithocenosis, laserray-irradiation and abrasion) emitting or generating high-frequencywaves, ultrasonics and hydraulic impulse waves; and a variety of sensorsand leading wires therefor.

[0072] In the medical tube according to the second embodiment of thepresent invention, the long tool 7 for medical treatments or diagnosesmay be connected to the cylindrical balloon 4 by directly connectingthese members, by indirectly connecting them through another tube or byindirectly connecting them through another tube which is laid acrossthese members.

[0073] The embodiment shown in FIG. 7 relates to an example in which anendoscope for observing biological tissues or the interior of tubularorgans is incorporated into the medical tube as the tool 7 for medicaltreatments or diagnoses. The endoscope comprises a light-transmittingfiber bundle 71 (light-guiding fiber bundle), a light-receiving fiberbundle 72 (image fiber bundle) and a lens 73 fitted to the tip of thelight-receiving fiber bundle 72. The tip of the light-transmitting fiberbundle 71 extends over the lens 73 and arrives at the tip of the medicaltube. Then the other end (tip) of the cylindrical balloon 4 isliquid-tightly connected to the light-transmitting fiber bundle 71 andthe lens 73 by an adhesive 74.

[0074] The medical tube according to the second embodiment of thepresent invention is free of any lumen which is opened at the tip of theshaft tube and therefore, this embodiment does not permit the injectionof a fluid into biological tissues or the interior of tubular organs orthe suction of a fluid therefrom. As has been explained above inconnection with the medical tube equipped with the balloon as shown inFIG. 4, however, the angle of bending and the shape of the bent balloonor the medical tube can arbitrarily be changed in proportion to thecontrolled pressure of the fluid pressure controller if the first lumen5, which communicates with the interior of the balloon 4, is connectedto the source of a pressing fluid through the fluid pressure controller,when practically using the medical tube, and the extent of the bendingcan continuously be changed in response to the fluid pressure. For thisreason, the medical tube allows the tool for medical treatments ordiagnoses to proceed to a desired direction. For instance, when themedical tube having a built-in endoscope is forced in a biologicaltubular cavity, the branching through which the tube may advance canappropriately be selected while observing and confirming with theendoscope to thus be able to precisely specify the site to be examined.Moreover, the medical tube has a quite simple structure and the diameterthereof can be made very small.

[0075] In the medical tube according to the second embodiment of thepresent invention, the angle of bending of the bent balloon or themedical tube can arbitrarily be changed in proportion to the controlledpressure applied by the fluid pressure controller and the pulse-likepressure-generating pulsatile pump if the first lumen 5, whichcommunicates with the interior of the balloon 4, is connected to thesource of a pressing fluid through the fluid pressure controller and tothe pulse-like pressure-generating pulsatile pump, when practicallyusing the medical tube, and the extent of the bending can continuouslybe changed in response to the fluid pressure and the pulsatile pressure,as has been explained above in connection with the medical tube shown inFIGS. 4 and 5. Accordingly, the balloon can guide the medical tubetowards a desired direction, while separating biological tissues andobserving and confirming them with the endoscope. Moreover, the medicaltube has a quite simple structure and the diameter thereof can be madevery small.

[0076]FIGS. 8 and 9 each is a cross sectional view showing a part of themedical tube according to a third embodiment of the present invention.The medical tube according to the third embodiment of the presentinvention comprises a shaft tube 3 which is inserted into a living body;a cylindrical balloon 4 whose one end is liquid-tightly connected to thetip of the shaft tube 3; and a long tool 7 for medical treatments ordiagnoses, whose tip portion is directly or indirectly connected,liquid-tightly, to the other end of the cylindrical balloon 4. A firstlumen 5 is formed within the shaft tube 3 and communicates with theinterior of the balloon 4 so that a fluid can pass therethrough and atleast one second lumen 6 is also formed within the shaft tube 3 and isopened at the periphery of the tip thereof. In addition, the long tool 7for medical treatments or diagnoses is accommodated in the first lumen5.

[0077] The long tool 7 for medical treatments or diagnoses is identicalto those described above in connection with the medical tube accordingto the second embodiment of the present invention and the tool 7 canlikewise be connected to the cylindrical balloon 4 by the same methodsexplained above. FIGS. 8 and 9 also show an embodiment having a built-inendoscope for observing biological tissues or the interior of thetubular organs, as the tool 7 for medical treatments or diagnoses andthe endoscope is also identical to that explained above.

[0078] The medical tube according to the third embodiment of the presentinvention comprises the lumen which is opened at the periphery of thetip of the shaft tube 3 and therefore, the tube permits the injection ofa fluid into biological tissues or tubular organs or the suction of afluid therefrom. Moreover, the angle of bending and the shape of thebent balloon or the medical tube provided with the balloon canarbitrarily be changed in proportion to the controlled pressure of thefluid pressure controller if the first lumen 5, which communicates withthe interior of the balloon 4, is connected to the source of a pressingfluid through the fluid pressure controller, when practically using themedical tube, as has been explained above in connection with the medicaltube equipped with the balloon as shown in FIG. 4 and the extent of thebending can continuously be changed in response to the fluid pressure.For this reason, the medical tube allows the tool for medical treatmentsor disgnoses to proceed to a desired direction. For instance, when themedical tube having a built-in endoscope is forced in a biologicaltubular cavity, the branching through which the tube can advance towardsa desired site can appropriately be selected while observing andconfirming with the endoscope to thus be able to precisely specify thesite to be examined. Moreover, the medical tube has a quite simplestructure and the diameter thereof can be made very small.

[0079] In the medical tube according to the third embodiment of thepresent invention, the angle of bending of the bent balloon or medicaltube can arbitrarily be changed in proportion to the controlled pressureapplied by the fluid pressure controller and the pulse-likepressure-generating pulsatile pump if the first lumen 5, whichcommunicates with the interior of the balloon 4, is connected to thesource of a pressing fluid through the fluid pressure controller and tothe pulse-like pressure-generating pulsatile pump, when practicallyusing the medical tube, and the extent of the bending can continuouslybe changed in response to the fluid pressure and the pulse-likepressure, as has been explained above in connection with the medicaltube shown in FIGS. 4 and 5. Accordingly, one can precisely specify thedirection along which the medical tube should be forced into biologicaltissues while separating the biological tissues and observing andconfirming the condition with the endoscope. Moreover, the medical tubehas a quite simple structure and the diameter thereof can be made verysmall.

[0080]FIG. 10 shows the balloon 4 of the medical tube, as shown in FIG.7, equipped with a balloon shown in FIG. 1, in its bent state, and morespecifically, the balloon which is bent toward the side of therelatively low stretchable section by connecting the first lumen 5communicating with the interior of the balloon 4 to the fluid pressuresource through the fluid pressure controller and injecting a fluid intothe balloon 4. The extent of the bending can continuously be changed inresponse to the magnitude of the fluid pressure.

[0081]FIG. 11 shows the balloon 4 of the medical tube equipped with aballoon shown in FIG. 4, which is bent in an S-shaped form, and morespecifically, the balloon 4 which is bent in an S-shaped form toward theside of the relatively low stretchable section by connecting the firstlumen 5 communicating with the interior of the balloon 4 to the fluidpressure source through the fluid pressure controller and injecting afluid into the balloon 4; or by connecting the lumen 5 to the pulse-likepressure-generating pulsatile pump and injecting a fluid into theballoon 4 in a series of pulses. The extent of the bending cancontinuously be changed in response to the magnitude of the fluidpressure.

[0082] The balloon for medical tubes according to the present inventionas well as applications thereof have been described above in detail withreference to the embodiments shown in the accompanying drawings, but thepresent invention is not restricted to these specific ones at all.

[0083] As has been discussed above in detail, the medical tube of thepresent invention does not require the use of any complicated structureand the diameter thereof can be made small. Moreover, the bending angleof the tip thereof is greatly affected by the fluid pressure applied andtherefore, the angle can freely be changed by controlling the pressure.Thus, the present invention can provide a medical tube having a variablebending ability and hence a direction-selecting function, one can thuspositively approach the medical tube to a desired site in biologicaltissues by appropriately adjusting the bending angle of the balloon andthe present invention can also provide a medical tube structure havingan ability of variable bending motions and an ability of separatingbiological tissues.

What is claimed is:
 1. A cylindrical balloon for medical tubes, which issusceptible to bending operations, comprising a low stretchable sectionformed, by a partial cross-linking treatment, on the balloon along thecircumferential direction thereof.
 2. The cylindrical balloon formedical tubes susceptible to bending operations as set forth in claim 1wherein the cross-linking treatment is a radiation cross-linkingtreatment.
 3. The cylindrical balloon for medical tubes susceptible tobending operations as set forth in claim 1 wherein the low stretchablesection formed by cross-linking extends over less than a half of thecircumferential region on the cylindrical balloon, along the axialdirection thereof.
 4. The cylindrical balloon for medical tubessusceptible to bending operations as set forth in claim 1 wherein afirst low stretchable section formed by a cross-linking treatmentpartially extends over less than a half of the circumferential region onthe cylindrical balloon, along the axial direction thereof, a second lowstretchable section formed by a cross-linking treatment partiallyextends over less than a half of the circumferential region on thecylindrical balloon, along the axial direction thereof, and the firstand second sections are circumferentially arranged in oppositedirections on the balloon and are arranged so that they are not in linewith each other in the axial direction of the balloon.
 5. Thecylindrical balloon for medical tubes susceptible to bending operationsas set forth in claim 4 wherein the first and second sectionssubstantially do not overlap with each other in the axial direction ofthe balloon.
 6. A medical tube equipped with a balloon comprising: ashaft tube for being inserted into a living body; a cylindrical balloonliquid-tightly connected to the shaft tube at the periphery of the tipthereof; a first lumen which is formed within the shaft tube and whichcommunicates with the interior of the balloon; and at least one secondlumen which is formed within the shaft tube and which is opened at thetip of the shaft tube; wherein the cylindrical balloon comprises a lowstretchable section which is formed on the circumferential region on theballoon by a partial cross-linking treatment.
 7. The medical tubeequipped with a balloon as set force in claim 6 wherein the cylindricalballoon used comprises a first low stretchable section formed by across-linking treatment, which partially extends over less than a halfof the circumferential region on the cylindrical balloon, along theaxial direction thereof; and a second low stretchable section formed bya cross-linking treatment, which partially extends over less than a halfof the circumferential region on the cylindrical balloon, along theaxial direction thereof, wherein the first and second sections arecircumferentially arranged in opposite directions on the balloon and arearranged so that they are not in line with each other in the axialdirection of the balloon.
 8. A medical tube equipped with a ballooncomprising: a shaft tube for being inserted into a living body; acylindrical balloon, one end of which is liquid-tightly connected to theshaft tube at the tip thereof; a long tool for medical treatments or fordiagnoses, whose tip portion is liquid-tightly connected to the otherend of the balloon directly or indirectly; and a first lumen which isformed within the shaft tube and communicates with the interior of theballoon so that a liquid can pass through the balloon and whichaccommodates the long tool for medical treatments or for diagnoses;wherein the cylindrical balloon comprises a low stretchable sectionwhich is partially formed on the circumferential region on the balloonby a cross-linking treatment.
 9. The medical tube equipped with aballoon as set forth in claim 8 wherein it further comprises at leastone second lumen which is formed within the shaft tube and is opened atthe periphery on the tip of the shaft tube.